CYANOPHAGE REGULATORY ELEMENTS ARE FUNCTIONAL IN THE PLASTIDIAL ENVIRONMENT, ALLOWING THE EXPRESSION OF HETEROLOGOUS PROTEINS

JUAREZ M; SEGRETIN ME; MIRKIN FG; BRAVO ALMONACID F; BOCCARDO NA

Congreso; XXXII Reunión Argentina y XVI Congreso Latinoamericano de Fisiología Vegetal; 2018

The expression of heterologous proteins by the transformation of the plastid genome is an interesting biotechnological strategy due to the potentially high expression levels (up to 70% of total soluble proteins). Only a few regulatory elements have proved to be efficient promoting the expression of transgenes in this organelle. Because of its evolutionary origin, chloroplasts share many characteristics with their cyanobacteria ancestors, including many aspects of gene regulation. To evaluate if regulatory elements of cyanophage (bacteriophages that infect cyanobacteria) origin are functional in the plastidial environment, we studied the promoter and 5?UTR of the psbA gene of the cyanophage S-PM2 in tobacco chloroplasts. In order to do this, we cloned these sequences in a plastid transformation vector upstream the uidA reporter gene and we transformed tobacco plastids. Bacteria and transplastomic plants that express β-glucuronidase under the regulatory control of (1) tobacco psbA promoter and 5?UTR, (2) tobacco psbA promoter and S-PM2 psbA 5?UTR, and (3) S-PM2 psbA promoter and 5?UTR are being evaluated, to determine functionality of S-PM2 regulatory elements to allow transcription and/or promote translation in the plastidial environment. We will be presenting results showing that cyanophage regulatory elements are functional in plastids of higher plants.